pytest-beartype-tests

2026.4.26 verified Sat May 09 auth: no python

A Pytest plugin that automatically applies @beartype to every collected test function at runtime, enabling runtime type-checking of test arguments and return values. The current version is 2026.04.26, with a rapid release cadence tied to calendar dates.

pip install pytest-beartype-tests

Common errors

error ModuleNotFoundError: No module named 'beartype' ↓

cause Missing beartype dependency

fix

pip install beartype

error pytest: error: unrecognized arguments: --beartype-tests ↓

cause Plugin not installed or not activated in pytest

fix

Install pytest-beartype-tests via pip; ensure it's in the same environment.

Warnings

gotcha Automatic application of @beartype may slow down test collection for large test suites. ↓

fix Use --beartype-tests-skip to selectively disable for certain directories.

gotcha The plugin applies beartype to ALL collected test functions, including fixtures and conftest hooks, which can cause unexpected failures if those functions lack annotations. ↓

fix Ensure all test functions have appropriate type annotations or use @beartype.skip on specific functions.

Imports

pytest_beartype_tests
wrong
```
from pytest_beartype_tests import *
```
correct
```
import pytest_beartype_tests
```
Plugin is auto-discovered; explicit import not needed.

Quickstart

Enable beartype checking on all test functions by passing --beartype-tests to pytest.

# test_example.py
import pytest

def test_addition(a: int, b: int) -> int:
    return a + b

# Run with: pytest --beartype-tests